In the area of varnishing and painting technology, so-called spray guns are used. These are devices that are supplied with both varnish or paint in liquid form as well as compressed air, and that distribute the varnish or the paint, with the addition of compressed air, in very small drops, the so-called spray jet with which the surface to be coated is covered. The addition of paint can, for example, take place with a paint hose, with so-called flow cups placed above, or with so-called siphon cups, suspended below. The paint is supplied from these cups or supply lines of a so-called paint nozzle, whose opening can be regulated by the user via a nozzle needle. The paint nozzle is surrounded by an air nozzle, which is designed as a ring nozzle and which is supplied with the compressed air. This leaves the ring nozzle at a high speed and thereby carries along the paint exiting from the paint nozzle, atomizes it, and in this way produces the fine spray jet. Such a varnishing or painting gun is the subject of EP 0710506 A1, whose disclosure content is made the subject of this description. The publication also shows, in FIG. 2, the precise structure of the paint nozzle and the ring nozzle, together with an air nozzle closure, which has an air cap.
With modern paint spray guns, the air nozzle closure is designed in such a way that it has an air cap, which has an axial borehole to hold the paint nozzle when screwed on, with the formation of an annular slot for the passage of exiting air and a first annular flange, directed radially outward. Furthermore, the air nozzle closure has an air nozzle ring surrounding the air cap, with a second annular flange directed radially inward and an inner thread for screwing on the air nozzle closure with an outer thread of the spray gun. The air cap, when screwed on, is snapped in, with annular flanges adjacent to one another, between the spray gun and the air nozzle ring. Furthermore, an annular groove with a locking ring is provided on the outside of the air cap; it locks the air nozzle ring against a loosening of the air cap when it is not screwed on wherein, therefore, the air nozzle ring is removed from the spray gun.
Such air nozzle closures have the disadvantage that the locking ring is hard to handle and thus, during the cleaning of the spray gun, it is hard to remove the air nozzle ring from the air cap.